Because of the requirements in semiconductor technology to form integrated circuits (IC's) with higher and higher integration densities, trench technology in IC's has attracted much attention. This technology offers additional device areas and an extra degree of freedom in designing semiconductor devices. Such technology in designing semiconductor devices may be seen, for example, in U.S. Pat. Nos. 4,437,226 or 4,756,793, as well as Japanese Patent Application No. 1-64336 A.
These references involve providing films on trench side walls for semiconductor devices.
Moreover, the concept of selective etching has been considered in the prior art, such as seen, for example, in Japanese Application No. 1-64336 A as well as U.S. Pat. No. 4,514,251. These various references involve various techniques for forming features in semiconductor technology which provides a basis for accomplishing the presently claimed invention. For example, while the various references discuss oxidation of trench surfaces, nowhere is there any discussion of providing selective growth of oxidation layers at different side walls of the trenches. This knowledge occurs from the present application.